There are many situations in which it is desired that a prototype or low-volume production tool be made from a master model constructed from relatively low heat-resistant material; that is, the material out of which the model is constructed either softens and/or melts at a relatively low temperature, or is combustible at comparatively low temperatures. Examples of such materials of construction for master models that would be desirably accommodated include wax, wood, plastic and similar materials.
It is known to use zinc alone in spray forming processes on such low heat-resistant materials, but the resulting tool is relatively soft because of its exclusive, or near-exclusive zinc content. As a result, tools of only very limited application may be formed in such a manner. These tools are normally limited to prototype applications because they do not possess sufficient durability to withstand even low-volume production manufacturing.
Conventional thermal spray form molding has utilized metals which require substantial energy input, which is typically manifest as heat energy, to moltenize and make the metal sprayable. Because of the high temperature of such a moltenized metal when it strikes the master model, the model has typically been required to be constructed from high heat tolerant material, such as ceramic, in order to survive the spraying of such molten metal thereupon. Because the original model is not typically cast directly in ceramic, multiple steps are required to finally establish a ceramic master model from one that has been constructed, for instance, by rapid prototyping methods such as stereo lithography, or which are constructed out of other types of low-heat resistant materials such as wood, wax and plastic laminate.
Because of the expense and delay associated with the usual multi-step process required to establish the ceramic master model, it is highly desirable to be able to perform spray form techniques directly upon the surface of an original model constructed from such rapid prototyping methods and low-heat resistant materials.